This invention relates to the production of composite mouldings.
The composite industry is commonly known as the grp (glass-reinforced plastics) industry, or the frp (fibre-reinforced plastics) industry and encompasses the production of composite mouldings for a large number of sectors of industrial application. These include the automotive, bus and truck, marine and aerospace industries. In these sectors, many composite moulded parts will have surface areas well in excess of 1 square meter. For example, a boat moulding could have a surface area within the range of from 10 to 1000 square meters.
The production of composites involves the use of two basic raw materials. One is a thermosetting liquid resin and the other is a fibre (usually a glass fibre). The traditional method of manufacture has involved laying the two materials in an open mould and consolidating them manually to the desired moulding thickness.
As a result of ever-increasing global legislation demanding reduction in hazardous conditions and dust, and general improvements in working conditions, the open moulding of composite parts is on the decline in favour of closed mould production methods. In these, a matched pair of moulds is employed to create a cavity between them such that, when the two moulds are held in closed registration, the defined cavity faithfully represents the shape and thickness of the desired mould part.
Closed mould sets vary within the industry, ranging from heavy duty rigid mould sets, which are designed to withstand high compression or resin injection pressures, to thin closed mould sets which are designed to be held together with the aid of vacuum within their cavities.
The large surface areas of these mould sets create manufacturing problems, i.e. it is difficult to maintain the required tolerance of part thickness and shape.
It is accordingly an object of the present invention to provide an improved method of making composite mouldings. It is also an object of the present invention to provide an improved form of composite closed mould production facility.
According to a first aspect of the present invention there is provided a method of making a composite moulding which includes:
providing a pair of mould elements which define a mould cavity,
introducing reinforcing fibre into the mould cavity,
feeding a resin mix into the mould cavity,
providing means for sensing distortion of a mould element and generating an output signal when a predetermined degree of distortion is sensed, and
controlling the rate at which the resin mix is introduced into the mould cavity in dependence on said output signal.
According to a second aspect of the present invention there is provided a composite closed mould production facility which includes:
a pair of mould elements which define a mould cavity into which reinforcing fibre can be introduced,
means for feeding a resin mix into the mould cavity,
means for sensing distortion of a mould element,
means for generating an output signal when a predetermined degree of distortion is sensed, and
control means for controlling the rate at which the resin mix is introduced into the mould cavity in dependence on said output signal.